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Grid/lib/algorithms/iterative/SchurRedBlack.h
Peter Boyle 28bdc90908 Sizable improvement in multigrid for unsquared.
6000 matmuls CG unprec
2000 matmuls CG prec (4000 eo muls)
1050 matmuls PGCR on 16^3 x 32 x 8 m=.01

Substantial effort on timing and logging infrastructure
2015-07-24 01:31:13 +09:00

117 lines
4.3 KiB
C++

#ifndef GRID_SCHUR_RED_BLACK_H
#define GRID_SCHUR_RED_BLACK_H
/*
* Red black Schur decomposition
*
* M = (Mee Meo) = (1 0 ) (Mee 0 ) (1 Mee^{-1} Meo)
* (Moe Moo) (Moe Mee^-1 1 ) (0 Moo-Moe Mee^-1 Meo) (0 1 )
* = L D U
*
* L^-1 = (1 0 )
* (-MoeMee^{-1} 1 )
* L^{dag} = ( 1 Mee^{-dag} Moe^{dag} )
* ( 0 1 )
* L^{-d} = ( 1 -Mee^{-dag} Moe^{dag} )
* ( 0 1 )
*
* U^-1 = (1 -Mee^{-1} Meo)
* (0 1 )
* U^{dag} = ( 1 0)
* (Meo^dag Mee^{-dag} 1)
* U^{-dag} = ( 1 0)
* (-Meo^dag Mee^{-dag} 1)
***********************
* M psi = eta
***********************
*Odd
* i) (D_oo)^{\dag} D_oo psi_o = (D_oo)^dag L^{-1} eta_o
* eta_o' = (D_oo)^dag (eta_o - Moe Mee^{-1} eta_e)
*Even
* ii) Mee psi_e + Meo psi_o = src_e
*
* => sol_e = M_ee^-1 * ( src_e - Meo sol_o )...
*
*/
namespace Grid {
///////////////////////////////////////////////////////////////////////////////////////////////////////
// Take a matrix and form a Red Black solver calling a Herm solver
// Use of RB info prevents making SchurRedBlackSolve conform to standard interface
///////////////////////////////////////////////////////////////////////////////////////////////////////
template<class Field> class SchurRedBlackDiagMooeeSolve {
private:
OperatorFunction<Field> & _HermitianRBSolver;
int CBfactorise;
public:
/////////////////////////////////////////////////////
// Wrap the usual normal equations Schur trick
/////////////////////////////////////////////////////
SchurRedBlackDiagMooeeSolve(OperatorFunction<Field> &HermitianRBSolver) :
_HermitianRBSolver(HermitianRBSolver)
{
CBfactorise=0;
};
template<class Matrix>
void operator() (Matrix & _Matrix,const Field &in, Field &out){
// FIXME CGdiagonalMee not implemented virtual function
// FIXME use CBfactorise to control schur decomp
GridBase *grid = _Matrix.RedBlackGrid();
GridBase *fgrid= _Matrix.Grid();
SchurDiagMooeeOperator<Matrix,Field> _HermOpEO(_Matrix);
Field src_e(grid);
Field src_o(grid);
Field sol_e(grid);
Field sol_o(grid);
Field tmp(grid);
Field Mtmp(grid);
Field resid(fgrid);
pickCheckerboard(Even,src_e,in);
pickCheckerboard(Odd ,src_o,in);
/////////////////////////////////////////////////////
// src_o = Mdag * (source_o - Moe MeeInv source_e)
/////////////////////////////////////////////////////
_Matrix.MooeeInv(src_e,tmp); assert( tmp.checkerboard ==Even);
_Matrix.Meooe (tmp,Mtmp); assert( Mtmp.checkerboard ==Odd);
tmp=src_o-Mtmp; assert( tmp.checkerboard ==Odd);
// get the right MpcDag
_HermOpEO.MpcDag(tmp,src_o); assert(src_o.checkerboard ==Odd);
//////////////////////////////////////////////////////////////
// Call the red-black solver
//////////////////////////////////////////////////////////////
std::cout<<GridLogMessage << "SchurRedBlack solver calling the MpcDagMp solver" <<std::endl;
_HermitianRBSolver(_HermOpEO,src_o,sol_o); assert(sol_o.checkerboard==Odd);
///////////////////////////////////////////////////
// sol_e = M_ee^-1 * ( src_e - Meo sol_o )...
///////////////////////////////////////////////////
_Matrix.Meooe(sol_o,tmp); assert( tmp.checkerboard ==Even);
src_e = src_e-tmp; assert( src_e.checkerboard ==Even);
_Matrix.MooeeInv(src_e,sol_e); assert( sol_e.checkerboard ==Even);
setCheckerboard(out,sol_e); assert( sol_e.checkerboard ==Even);
setCheckerboard(out,sol_o); assert( sol_o.checkerboard ==Odd );
// Verify the unprec residual
_Matrix.M(out,resid);
resid = resid-in;
RealD ns = norm2(in);
RealD nr = norm2(resid);
std::cout<<GridLogMessage << "SchurRedBlackDiagMooee solver true unprec resid "<< std::sqrt(nr/ns) <<" nr "<< nr <<" ns "<<ns << std::endl;
}
};
}
#endif